LowestCommonMultiple

[Viper]

**Recursion must be used**
The LCM (lowest common multiple ) of two non-zero integers can be found using the formula: lcm(num1, num2) = num1*num2/ gcd(num1, num2) where: gcd(num1, num2) is the greatest common divisor of num1 and num2. here's the trick. the program should employ a recursive approach to finding the gcd of two number. The recursive definition is given by:
if num2 divides evenly into num1 then
gcd= num2

could someone re-write tht in C++ for me plz

here it is in turing

code:

var lcm, gcd : real := 0 var num1, num2 : int := 0 %------------------------------------------------------------------------------------------ proc starter     put "Enter the numbers you wish to find the 'LCM' for"     put "***********Hit enter after each number**********"     get num1     get num2 end starter %------------------------------------------------------------------------------------------ proc GCD (num1, num2 : real)     if num1 mod num2 = 0 then         gcd := num2     else         GCD (num2, num1 mod num2)     end if end GCD %------------------------------------------------------------------------------------------ proc LCM (gcd, num1, num2 : real)     lcm := num1 * num2 / gcd     put "The 'LCM' for", " ", num1, " ", "&", " ", num2, " ", "is", " ", lcm     put "The 'GCD' for", " ", num1, " ", "&", " ", num2, " ", "is", " ", gcd end LCM %MAIN----------------------------------- starter GCD (num1, num2) LCM (gcd, num1, num2)

[[Gandalf]]

No. Try it yourself first.

[Geminias]

here you go



syntax = c++

code:

#include <iostream> void intro (); float module (); float lcm (float GCD); void intro () {      int num1 = 0, num2 = 0, N1 = 0, N2 = 0;      int *pNum1 =  num1;      int *pNum2 =  num2;      int *pN1 =  N1;      int *pN1 =  N2;                  std::cout << "Enter the numbers you wish to find the LCM for" << std::endl  <<      "********Hit enter after each number*********<< std::endl << std::endl;            std::cin >> num1;      std::cin >> num2;      N1 = num1;      N2 = num2; } float module () {       float gcd;        if (*pNum1 % *pNum2 == o)    {         gcd = *pNum2;    }      else    {           *pNum1 = *pNum2;        *pNum2 = *pNum1 % *pNum2;        module ();    }        return gcd; } float lcm(float GCD) {       lcm = *pNum2 * (*pNum1) / GCD;       return lcm; } int main () {     intro();     std::cout << "The LCM for " << *pN1 << " and " << *pN2 << " is " << lcm (module()) << std::endl;     std::cout << "The GCM for " << *pN1 << " and " << *pN2 << " is " << lcm (module()) << std::endl;

[wtd]

Wow...

c++:

float module () {    float gcd;      if (*pNum1 % *pNum2 == o)    {       gcd = *pNum2;    }    else    {          *pNum1 = *pNum2;       *pNum2 = *pNum1 % *pNum2;       module ();    }        return gcd; }

Where do you think pNum1 and pNum2 are coming from? I don't see a declaration for them in the function. Nor do I see a declaration for them in the global scope.

c++:

std::cout << "Enter the numbers you wish to find the LCM for" << std::endl      "********Hit enter after each number*********<< std::endl << std::endl;

You have this, which makes no sense, since you're missing an insertion operator.

You don't have a closing brace at the end of "main".

Is there any particular reason you thought this code would work?

[Geminias]

yeah i honestly thought pointers would last forever until i deleted them lol

i just tested and realized they don't...

plus yeah there is a whole score of syntax errors

[wtd]

Research the concept of "scope".

[Geminias]

i think i understand scope but i misunderstood how a pointer works. i thought the specific purpose of a pointer was to access private data. Which, maybe it is, but i should declare the pointers as global. i'll check as soon as i have time

[wtd]

Geminias wrote:

i think i understand scope but i misunderstood how a pointer works. i thought the specific purpose of a pointer was to access private data. Which, maybe it is, but i should declare the pointers as global. i'll check as soon as i have time

No, you should not declare variables (a pointer is just a variable) globally. Learn how to pass things via arguments.

[Geminias]

hey again, yeah i dropped out the idea of pointers and functions for this.
it finds the lowest common multiple and the highest common multiple (LCM) (GCM) but it excludes 1. Because 1 divides into everything.
in the case that only one number besides 1 is common to both numbers, then LCM = GCM.

Viper, your recursion technique did not work. It does not find the LCM and GCM.

try this.... (note: if one of the numbers is prime the program crashes.)

syntax = c++

code:

#include <iostream> int main () {     unsigned long int num1, num2, gcm,lcm;     std::cout << "Enter two numbers starting with the highest one." << std::endl <<     "*********hit enter after each number**************" << std::endl << std:: endl;         std::cin >> num1;     std::cin >> num2;     gcm = 1;     for (int i = num2; i >= gcm ; i--)   {         if (num2 % i == 0 && num1 % i == 0)      {   gcm = i;       }      else if (i = 1)     {            gcm = 1      }   }      for (int i = 2; i <= num2; i++)    {          if (num2 % i == 0 && num1 % i ==0)          {               lcm = i;               i = num2;          }          else if (i = num2)         {              lcm = 1;          }    }    std::cout << "The LCM is: " << lcm << std::endl;    std::cout << "The GCM is: " << gcm << std::endl;    std::cin.ignore(1,'\n');    std::cin.ignore();          return 0; }

[wtd]

What is "Greatest Common Multiple"? Infinity?

code:

$ ./a.ut Enter two numbers starting with the highest one. *********hit enter after each number************** 4 3 The LCM is: 0 The GCM is: 1

For a cleaned up version of your code.

c++:

#include <iostream> int main () {     unsigned long int num1, num2, gcm,lcm;     std::cout << "Enter two numbers starting with the highest one."   << std::endl               << "*********hit enter after each number**************" << std::endl               << std:: endl;         std::cin >> num1;     std::cin >> num2;     gcm = 1;         for (int i = num2; i > gcm ; i--)     {         if (num2 % i == 0 && num1 % i == 0)         {             gcm = i;         }     }         for (int i = 2; i < num2; i++)     {         if (num2 % i == 0 && num1 % i ==0)         {             lcm = i;             i = num2;         }     }     std::cout << "The LCM is: " << lcm << std::endl;     std::cout << "The GCM is: " << gcm << std::endl;         return 0; }

[wtd]

I'm not going to give you working C++ code for this, but I will show you the algorithm.

code:

# let rec gcd num1 num2 =      if num1 > num2 then         if num1 mod num2 = 0 then            num2         else            gcd (num1 mod num2) num2      else         gcd num2 num1;; val gcd : int -> int -> int = <fun> # gcd 12 8;; - : int = 4 # gcd 2336 1314;; - : int = 146 # let lcm num1 num2 = num1 * num2 / gcd num1 num2;; val lcm : int -> int -> int = <fun> # lcm 57 12;; - : int = 228 # 57 * 12;; - : int = 684

You may also wish to hit Google. Never know what you'll find.

[Geminias]

i fixed the logic so it will return 1 as both lcm and gcm in the case that there are no other common multiples.

hey wtd, how do you get all that pretty color in your code lol

[Andy]

use code tags instead of [code ] use [sytax="cpp" ]

[Geminias]

Geminias wrote:

hey again, yeah i dropped out the idea of pointers and functions for this.
it finds the lowest common multiple and the highest common multiple (LCM) (GCM) but it excludes 1. Because 1 divides into everything.
in the case that only one number besides 1 is common to both numbers, then LCM = GCM.

Viper, your recursion technique did not work. It does not find the LCM and GCM.

try this.... (note: if one of the numbers is prime the program crashes.)

syntax = c++

c++:

#include <iostream> int main () {     unsigned long int num1, num2, gcm,lcm;     std::cout << "Enter two numbers starting with the highest one." << std::endl <<     "*********hit enter after each number**************" << std::endl << std:: endl;         std::cin >> num1;     std::cin >> num2;     gcm = 1;     for (int i = num2; i >= gcm ; i--)   {         if (num2 % i == 0 && num1 % i == 0)      {   gcm = i;       }      else if (i = 1)     {            gcm = 1      }   }      for (int i = 2; i <= num2; i++)    {          if (num2 % i == 0 && num1 % i ==0)          {               lcm = i;               i = num2;          }          else if (i = num2)         {              lcm = 1;          }    }    std::cout << "The LCM is: " << lcm << std::endl;    std::cout << "The GCM is: " << gcm << std::endl;    std::cin.ignore(1,'\n');    std::cin.ignore();          return 0; }

[Geminias]

thanks